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A371776
a(n) = Sum_{k=0..floor(n/3)} binomial(5*n-k+1,n-3*k).
3
1, 6, 55, 561, 6005, 66080, 740342, 8400074, 96206994, 1109874635, 12877808194, 150122945518, 1756887201266, 20628519611407, 242891806678851, 2866906127955287, 33910670558191711, 401857349039547372, 4770115555036932777, 56706219260783415643
OFFSET
0,2
FORMULA
a(n) = [x^n] 1/(((1-x)^2-x^3) * (1-x)^(4*n)).
PROG
(PARI) a(n) = sum(k=0, n\3, binomial(5*n-k+1, n-3*k));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Apr 05 2024
STATUS
approved